Data processing systems, such as personal computers, tablet computers, entertainment systems, game consoles, and cellular telephones, commonly include a human interface device (HID) for data input and/or controlling cursor movement. One widely utilized HID is a touch pad or touchscreen utilizing a capacitive sensing system to detect and measure proximity, position, displacement, or acceleration of a conductive object, such as a finger or stylus. Capacitive sensing systems generally include multiple capacitive sensing elements, a measurement circuit configured to measure a change in mutual capacitance between sensing elements or a change in the self-capacitance of the sensing elements, a switching circuit to selectively couple sensing elements to the measurement circuit, a conversion circuit to convert analog changes in capacitance to digital signals or values, and a controller or processor to configure components of the capacitive sensing system and to convert changes in sensed capacitance to changes in reported proximity, position, displacement, or acceleration of one or more proximate conductive objects.
In existing capacitive sensing systems all configurations are performed by the processor as part of standard in-line code, and must be performed before a conversion process can be started. Thus, if the processor is busy servicing an interrupt or other hardware (e.g., communications interface, haptics drivers) at the time that the other components of the capacitive sensing system becomes available, the capacitive sensing system will sit idle until the processor completes its current operation, unloads results from the last conversion, loads the new conversion configuration, and then enables the conversion to start. This in turn increases response time of a touchscreen utilizing the capacitive sensing system.